Model studies directed towards the synthesis of functionalised chiral A-ring derivatives of taxanes

Model studies, starting from the monoterpene R-carvone, directed towards the synthesis of chiral A-ring derivatives of taxanes with oxygen functionalities at C-2, 9 and 13 carbon atoms as in taxol is described.

Novel materials synthesis by mechanical alloying/milling

An account is given of the research that has been carried out on mechanical alloying/milling (MA/MM) during the past 25 years. Mechanical alloying, a high energy ball milling process, has established itself as a viable solid state processing route for the synthesis of a variety of equilibrium and non-equilibrium phases and phase mixtures. The process was initially invented for the production of oxide dispersion strengthened (ODS) Ni-base superalloys and later extended to other ODS alloys. The success of MA in producing ODS alloys with better high temperature capabilities in comparison with other processing routes is highlighted. Mechanical alloying has also been successfully used for extending terminal solid solubilities in many commercially important metallic systems. Many high melting intermetallics that are difficult to prepare by conventional processing techniques could be easily synthesised with homogeneous structure and composition by MA. It has also, over the years, proved itself to be superior to rapid solidification processing as a non-equilibrium processing tool. The considerable literature on the synthesis of amorphous, quasicrystalline, and nanocrystalline materials by MA is critically reviewed. The possibility of achieving solid solubility in liquid immiscible systems has made MA a unique process. Reactive milling has opened new avenues for the solid state metallothermic reduction and for the synthesis of nanocrystalline intermetallics and intermetallic matrix composites. Despite numerous efforts, understanding of the process of MA, being far from equilibrium, is far from complete, leaving large scope for further research in this exciting field.

Synthesis, Structures, and Magnetic Behavior of a Series of Copper(II) Azide Polymers of Cu-4 Building Clusters and Isolation of a New Hemiaminal Ether as the Metal Complex

Four new neutral copper azido polymers, Cu-4(N-3)(8)(L-1)(2)](n) (1), Cu-4(N-3)(8)(L-2)(2)](n) (2), Cu-4(N-3)(8)(L-3)(2)](n) (3), and Cu-9(N-3)(18)(L-4)(4)](n) (4) L1-4 are formed in situ by reacting pyridine-2-carboxaldehyde with 22-(methylamino)ethyl]pyridine (mapy, L-1), N,N-dimethylethylenediamine (N,N-dmen, L-2), N,N-diethylethylenediamine (N,N-deen, L-3), and N,N,2,2-tetramethylpropanediamine (N,N,2,2-tmpn, L-4)], have been synthesized by using 0.5 mol equiv of the chelating tridentate ligands with Cu-(NO3)(2)center dot 3H(2)O and an excess of NaN3. Single-crystal X-ray structures show that the basic unit of these complexes, especially 1-3, contains very similar Cu-4(II) building blocks. The overall structure of 3 is two-dimensional, while the other three complexes are one-dimensional in nature. Complex 1 represents a unique example containing hemiaminal ether arrested by copper(R). Complexes 1 and 2 have a rare bridging azido pathway: both end-on and end-to-end bridging azides between a pair of Cu-II centers. Cryomagnetic susceptibility measurements over a wide range of temperature exhibit dominant ferromagnetic behavior in all four complexes. Density functional theory calculations (B3LYP functional) have been performed on complexes 1-3 to provide a qualitative theoretical interpretation of their overall ferromagnetic behavior.

Preliminary studies on the synthesis and characterisation of hydroxyapatites

Synthesis of calcium hydroxyapatite Ca-10(PO4)(6)(OH)(2) ceramic powders by a solid state reaction between commercially available tricalcium phosphate and calcium hydroxide powders has been attempted in the range 700-1000 degrees C. Reaction of tricalcium phosphate and calcium hydroxide in 3:2 molar ratio at 1000 degrees C leads to the formation of pure calcium hydroxyapatite phase. The sample has been characterised by XRD and IR spectral studies. The compacted powder is sintered to 93% of theoretical density when fired in air at 1300 degrees C for 2 hours.

Enantioselective total synthesis of iso-cladospolide B, cladospolide C and cladospolide B from tartaric acid

The enantioselective synthesis of the natural products cladospolide B, cladospolide C, and iso-cladospolide B has been accomplished from tartaric acid. Key reactions in the synthetic sequence include the elaboration of a gamma-hydroxy amide derived from tartaric acid via alkene cross metathesis, Yamaguchi lactonization, and ring closing metathesis. (C) 2011 Elsevier Ltd. All rights reserved.

Microwave Assisted Synthesis and Antimicrobial Study of Schiff Base Vanadium(IV) Complexes of Phenyl Esters of Amino Acids

Schiff base vanadium(IV) complexes of phenyl esters of the two acidic amino acids, i.e., aspartic and glutamic acid, were synthesized. The phenyl esters of these amino acids were synthesized by conventional method whereas the Schiff base vanadium(IV) complexes were synthesized using microwave irradiation. The complexes were characterized by spectroscopic tools such as IR, 1H NMR, mass (ES), ESR, and UV visible spectroscopy. All the complexes were studied for antibacterial and antifungal activity and found to be moderately active.

Synthesis and structural characterization of perovskite 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) nanotubes

We report the synthesis and structural characterization of 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3) (PMN-PT) nanotubes prepared by a novel sal-gel template method. X-ray diffraction (XRD) and selected-area electron diffraction (SAED) investigations demonstrated that the postannealed (650 degrees C for 1 h) PMN-PT nanotubes were polycrystalline with perovskite crystal structure. The field emission scanning electron microscope (FE-SEM) shows that as prepared PMN-PT nanotubes were hollow with diameter to be about 200 nm. High resolution transmission electron microscope (HRTEM) analysis confirmed that the obtained PMN-PT nanotubes made up of nanoparticles (10-20 nm) which were randomly aligned in the nanotubes. Energy-dispersive X-ray spectroscopy (EDX) analysis confirmed the stoichiometric 0.65Pb(Mg1/3Nb2/3)O-3-0.35PbTiO(3). The possible formation mechanism of PMN-PT nanotubes was proposed at the end. (C) 2011 Elsevier B.V. All rights reserved.

Controlled synthesis of CuO nanostructures on Cu foil, rod and grid

CuO nanowires are synthesized by heating Cu foil, rod and grid in ambient without employing a catalyst or gas flow at temperatures ranging from 400 to 800 degrees C for a duration of 1-12 h. Scanning electron microscopy (SEM) investigation reveals the formation of nanowires. The structure, morphology and phase of the as-synthesized nanowires are analyzed by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). It is found that these nanowires are composed of CuO phase and the underlying film is of Cu2O. A systematic study is carried out to find the possibilities for the transformation of one phase to another completely. A possible growth mechanism for the nanowires is also discussed. (C) 2011 Elsevier B.V. All rights reserved.

Nanoporous alloy aggregates: synthesis and electrocatalytic activity

Nanoporous structures are widely used for many applications and hence there have been several efforts directed towards their synthesis. While several template-based and template-less approaches are available for monometallic systems, there is no general method for the synthesis of nanoporous multicomponent systems/alloys. We present a general template-less strategy for the synthesis of nanoporous alloy aggregates by controlled aggregation of nanoparticles in the solution phase with excellent control over morphology and composition as illustrated using AuPt, AuPd, PdPt and PtRu systems as examples. The Pt-based nanoporous clusters exhibit excellent activity for methanol oxidation with good long-term stability and CO tolerance. We show that the method can be extended to produce ternary catalysts and hence we expect our method to be widely used for the synthesis of multifunctional nanoporous structures for catalysis, sensor and drug-delivery applications.

Synthesis and biological evaluation of novel 2-aralkyl-5-substituted-6-(4 `-fluorophenyl)-imidazo2,1-b]1,3,4]thiadiazole derivatives as potent anticancer agents

Levamisole, the imidazo2,1-b]thiazole derivative has been reported as a potential antitumor agent. In the present study, we synthesized, characterized and evaluated biological activity of its novel analogues with substitution in the aralkyl group and on imidazothiadiazole molecules with same chemical backbone but different side chains namely 2-aralkyl-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]thiadiazoles (SCR1), 2-aralkyl-5-bromo-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-thiadiaz oles (SCR2), 2-aralkyl-5-formyl-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-thiadia zoles (SCR3) and 2-aralkyl-5-thiocyanato-6-(4'-fluorophenyl)-imidazo2,1-b]1,3,4]-th iadiazoles (SCR4) on leukemia cells. The cytotoxic studies showed that 3a, 4a, and 4c exhibited strong cytotoxicity while others had moderate cytotoxicity. Among these we chose 4a (IC50, 8 mu M) for understanding its mechanism of cytotoxicity. FACS analysis in conjunction with mitochondrial membrane potential and DNA fragmentation studies indicated that 4a induced apoptosis without cell cycle arrest suggesting that it could be used as a potential chemotherapeutic agent. (C) 2011 Elsevier Masson SAS. All rights reserved.